1. Field of the Invention
The invention is directed to a reference electrode for an electrochemical three-electrode sensor that is essentially made of a shaft with a platinum electrode embedded therein.
2. Description of the Prior Art
In most electrochemical three-electrode sensors, an air electrode is used as a reference system. This air electrode is realized in a simple manner and is also sufficiently stable for most applications. Such an air electrode is described, for example, in U.S. Pat. No. 3,909,386. However, its use is restricted to applications in which there is a sufficient partial pressure in oxygen. Furthermore, air reference electrodes also react to a number of other gases with fluctuations in potential resulting in a source of systematic error. Attempts have been made to overcome this source of systematic error by constructional measures, but experience has shown that it is difficult to eliminate these errors entirely.